U.S. patent application number 11/721500 was filed with the patent office on 2009-03-19 for coated substrate and method of making same.
This patent application is currently assigned to E.I. du Pont de Nemours and Company. Invention is credited to Paul Anthony Sant, Matthew Stainer.
Application Number | 20090072713 11/721500 |
Document ID | / |
Family ID | 36615265 |
Filed Date | 2009-03-19 |
United States Patent
Application |
20090072713 |
Kind Code |
A1 |
Sant; Paul Anthony ; et
al. |
March 19, 2009 |
COATED SUBSTRATE AND METHOD OF MAKING SAME
Abstract
Provided are containment structures having a substrate structure
having a plurality of walls extending from a surface to define a
space, wherein at least one of the walls has an overall negative
slope; a first layer deposited in the space having a first surface
energy no greater and a second layer deposited on top of the first
layer.
Inventors: |
Sant; Paul Anthony; (Santa
Barbara, CA) ; Stainer; Matthew; (Goleta,
CA) |
Correspondence
Address: |
WOODCOCK WASHBURN LLP
CIRA CENTRE, 12TH FLOOR, 2929 ARCH STREET
PHILADELPHIA
PA
19104-2891
US
|
Assignee: |
E.I. du Pont de Nemours and
Company
Wilmington
DE
|
Family ID: |
36615265 |
Appl. No.: |
11/721500 |
Filed: |
December 21, 2005 |
PCT Filed: |
December 21, 2005 |
PCT NO: |
PCT/US05/47261 |
371 Date: |
May 12, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60640817 |
Dec 29, 2004 |
|
|
|
60694875 |
Jun 28, 2005 |
|
|
|
Current U.S.
Class: |
313/504 ; 427/58;
428/34.1; 428/35.7 |
Current CPC
Class: |
Y10T 428/1352 20150115;
Y10T 428/13 20150115; H01L 51/0003 20130101; H01L 27/3246 20130101;
H01L 27/3283 20130101 |
Class at
Publication: |
313/504 ;
428/34.1; 428/35.7; 427/58 |
International
Class: |
H01J 1/62 20060101
H01J001/62; B32B 1/08 20060101 B32B001/08; B05D 5/12 20060101
B05D005/12 |
Claims
1. A containment structure comprising: a substrate structure having
a plurality of walls extending from a surface to define a space,
wherein at least one of the walls has an overall negative slope; a
first layer deposited in the space having a first surface energy no
greater than 30 mN/m; and a second layer deposited on top of the
first layer.
2. The containment structure of claim 1, wherein the first layer
has a surface energy of no greater than 25 mN/m.
3. The containment structure of claim 1, wherein the first layer
has a surface energy of no greater than 20 mN/m.
4. The containment structure of claim 1, wherein the second layer
comprises a polymer.
5. The containment structure of claim 1, wherein the first layer
comprises a fluorinated or sulfonated polymer.
6. The containment structure of claim 5, wherein the first layer
comprises a fluorinated polymer.
7. The containment structure of claim 1, wherein the wall has an
initial slope along the wall at the bottom of the space, wherein
the initial slope is more vertical compared to the overall
slope.
8. The containment structure of claim 1, wherein the substrate
structure has a second surface energy along a wall that is greater
than the first surface energy.
9. The containment structure of claim 1, further comprising an
organic active layer over the second layer.
10. The containment structure of claim 9, wherein the substrate
structure has a third surface energy along a wall, wherein the
third surface energy is greater than the first surface energy and
less than the second surface energy.
11. An organic electronic device comprising a containment structure
of claim 1.
12. An article useful in the manufacture of an organic electronic
device, comprising the containment structure of claim 1.
13. The article of claim 12, wherein the first layer of the
containment structure comprises a fluorinated or sulfonated
polymer.
14. A method for forming an electronic device comprising: providing
a substrate structure having a plurality of walls extending from a
surface to define a space, wherein at least one of the walls has an
overall negative slope; forming a first layer within the space,
wherein the first layer has a first surface energy no greater than
30 mN/m; depositing a liquid composition on the first layer and
within the space, wherein a liquid medium within the liquid
composition has a second surface energy that is greater than the
first surface energy; and evaporating a substantial portion of the
liquid medium to form a second layer.
15. The method of claim 14 where essentially all of the liquid
medium is evaporated.
16. The method of claim 14, wherein the first layer has a first
surface energy of no greater than 20 mN/m.
17. The method of claim 14, further comprising forming an organic
active layer over the second layer.
18. The method of claim 14, wherein the second layer comprises a
polymer.
19. The method of claim 14, wherein the first layer comprises a
fluorinated or sulfonated polymer.
20. The method of claim 14, wherein the surface energy of the
second layer is at least 15 mN/m greater than the surface energy of
the first layer.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation in part of U.S. patent
application Ser. No. 10/669,403, filed Sep. 24, 2003, U.S. patent
application Ser. No. 10/669,404 filed on Sep. 24, 2003, and U.S.
patent application Ser. No. 10/910,496, filed on Aug. 3, 2004. This
application also claims priority to U.S. Provisional Application
Nos. 60/640,817, filed Dec. 29, 2004 and 60/694,875, filed Jun. 28,
2005. The disclosures of each of the aforementioned applications
are incorporated herein by reference in their entireties.
FIELD OF THE DISCLOSURE
[0002] This disclosure relates generally to coatings of materials
on low energy surfaces, for example, those found in organic
electronic devices, and materials and methods for fabrication of
the same.
BACKGROUND INFORMATION
[0003] Organic electronic devices convert electrical energy into
radiation, detect signals through electronic processes, convert
radiation into electrical energy, or include one or more organic
semiconductor layers. The manufacturing of electronic components
that include organic layers, however, can be difficult, especially
when coating over a low energy surface.
[0004] Thus, what is needed are additional coating methods for
forming layers of an organic electronic device.
SUMMARY
[0005] In one embodiment, provided are containment structures
having:
[0006] a substrate structure having a plurality of walls extending
from a surface to define a space, wherein at least one of the walls
has an overall negative slope;
[0007] a first layer deposited in the space having a first surface
energy no greater than 30 mN/m; and
[0008] a second layer deposited on top of the first layer
[0009] The foregoing general description and the following detailed
description are exemplary and explanatory only and are not
restrictive of the invention, as defined in the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Embodiments are illustrated in the accompanying figures to
improve understanding of concepts as presented herein.
[0011] FIGS. 1 and 2 include illustrations of a plan view and a
cross-sectional view, respectively, of a portion of a prior art
containment structure.
[0012] FIGS. 3, 5, 6 and 7 include illustrations of a
cross-sectional view, a plan view, a plan view, and a
cross-sectional view of a portion of an exemplary embodiment of a
containment structure before, during, and after a liquid
composition is placed within the containment structure.
[0013] FIGS. 4 and 8 include illustrations of cross-sectional views
of the containment structure of FIGS. 3, 5, 6, and 7 before an
after a liquid composition comes in contact with an edge having a
negative slope.
[0014] FIGS. 9 and 10 include illustrations of a plan view and a
cross-section view, respectively, of a portion of a substrate after
forming first electrodes over the substrate.
[0015] FIGS. 11 and 12 include illustrations of a plan view and a
cross-section view, respectively, of the substrate of FIGS. 9 and
10 after forming a containment structure over the substrate and
first electrode.
[0016] FIGS. 13 and 14 include cross-sectional views illustrating
exemplary containment structure patterns.
[0017] FIG. 15 includes an illustration of a plan view of the
substrate of FIGS. 11 and 12 after forming a separator structure
over the substrate, first electrode, and containment structure.
[0018] FIGS. 16, 17, and 18 include illustrations of cross-section
views at sectioning lines 16-16, 17-17 and 18-18, respectively, of
FIG. 15.
[0019] FIGS. 19 and 20 include illustrations of a plan view and a
cross-section view, respectively, of the substrate of FIG. 15 after
forming organic layers over the substrate, first electrode,
containment structure, and separator structure.
[0020] FIGS. 21, 22, and 23 include illustrations of a plan view,
across-sectional view, and cross-sectional views, respectively, of
the substrate of FIGS. 19 and 20 after forming a second electrode
over the substrate, first electrode, containment structure,
separator structure, and organic layers.
[0021] FIGS. 24 and 25 include illustrations of a plan view and
across-section view, respectively, of a portion of an active-matrix
display having a common electrode.
[0022] The figures are provided by way of example and are not
intended to limit the invention. Skilled artisans appreciate that
objects in the figures are illustrated for simplicity and clarity
and have not necessarily been drawn to scale. For example, the
dimensions of some of the objects in the figures may be exaggerated
relative to other objects to help to improve understanding of
embodiments.
DETAILED DESCRIPTION
[0023] In one embodiment, provided containment structures
having:
[0024] a substrate structure having a plurality of walls extending
from a surface to define a space, wherein at least one of the walls
has an overall negative slope;
[0025] a first layer deposited in the space having a first surface
energy no greater than 30 mN/m; and
[0026] a second layer deposited on top of the first layer
[0027] In one embodiment, the first layer has a surface energy of
no greater than 25 mN/m. In one embodiment, the first layer has a
surface energy of no greater than 20 mN/m. In yet other
embodiments, the first layer has a surface energy of no greater
than 19 mN/m.
[0028] In one embodiment, the second layer comprises a polymer.
[0029] In one embodiment, the first layer comprises a sulfonated or
fluorinated polymer.
[0030] In one embodiment, the wall has an initial slope along the
wall at the bottom of the opening, wherein the initial slope is
more vertical compared to the overall slope.
[0031] In one embodiment, the substrate structure has a second
surface energy along a wall of the opening that is greater than the
first surface energy in some embodiments.
[0032] In one embodiment, the first layer lies within the opening
and does not underlie a base of the substrate structure.
[0033] One embodiment further comprises an organic active layer
over the second layer.
[0034] In one embodiment, the substrate structure has a third
surface energy along a wall of the opening, wherein the third
surface energy is greater than the first surface energy and less
than the second surface energy.
[0035] Also provided is a method for forming the aforementioned
electronic devices. In some embodiments, the method comprises:
[0036] providing a substrate structure having a plurality of walls
extending from a surface to define a space, wherein at least one of
the walls has an overall negative slope;
[0037] forming a first layer within the space, wherein the first
layer has a first surface energy no greater than 30 mN/m;
[0038] depositing a liquid composition on the first layer and
within the space, wherein a liquid medium within the liquid
composition has a second surface energy that is greater than the
first surface energy; and
[0039] evaporating a substantial portion of the liquid medium to
form a second layer.
[0040] In some embodiments, the surface energy of the second layer
is at least 15 mN/m greater than the surface energy of the first
layer.
[0041] In one embodiment essentially all of the liquid medium is
evaporated.
[0042] In one embodiment, the method further comprises forming an
organic active layer over the second layer.
[0043] Also provided are electronic devices and articles useful in
the construction of electronic devices containing at least one
containment structure described herein. Articles useful in the
construction of electronic devices can be later modified with
additional layers or components to form an electronic device.
[0044] Wetabiligy of a surface is important in achieving a uniform
coating. For example, if the surface is Teflon.RTM., the surface
energy could have a surface energy of 20 mN/m. If the solid-liquid
Interfacial energy is zero, the surface tension of the liquid must
also be 20 mN/m for wetting to occur. If the solid-liquid
interfacial energy is non-zero the surface tension of the liquid
must be lower by that amount for wetting to occur. For example,
when the solid-liquid interfacial energy is 3 mN/m, then the
surface tension would need to be 17 mN/m for wetting to occur.
[0045] In order to spontaneously wet a low energy surface having a
surface energy of 19 mN/m, a solvent who's surface tension is equal
to or lower than 19 mN/m is needed depending on what the
solid-liquid interfacial energy is. The instant invention uses the
dynamics of wetting inside the undercut structure. For a high
energy surface like glass (say 60 mN/m) wetting by solvents like
Mesitylene (29 mN/m) is no problem since the surface energy of
glass is greater then the combined sum of the solvent surface
tension and the interfacial solid-liquid energy.
[0046] The instant invention uses an additional force to achieve
wetting of a low energy surface, and that force comes from the
"pinning" of the contact line where the liquid meets the undercut
structure and isn'table to pull away and bead on the surface. Thus
wetting can be achieved with liquids whose surface tensions are
much higher then the surface energy of the solid surface that is
being coated. For example, solvents like Mesitylene (29 mN/m) or
Anisole (35 mN/m) can be used and still get wetting on a surface
having a surface energy of 19 mN/m. Without use of the instant
invention, solvents with surface tensions equal to or less then 19
mN/m would be needed to achieve uniform complete films.
[0047] FIG. 1 illustrates a plan view of a prior art containment
structure 102 and FIG. 2 illustrates a cross-sectional view of the
prior art containment structure 102. The containment structure 102
has a perimeter having a positive slope as seen from the
cross-sectional view of FIG. 2. When an organic composition 106, in
liquid form, is deposited into the area formed by the surrounding
containment structure 102, it may form voids. Such voids decrease
the available surface area for radiation emission or radiation
absorption, leading to reduced performance. Voids, such as void
108, may also expose underlying structures 104, such as electrodes.
When additional layers are formed over organic layers resulting
from curing the organic composition 106, these layers may contact
the underlying structure 104, permitting electrical shorting
between electrodes and rendering an affected organic electronic
component inoperable.
[0048] In addition, if containment structure 102 is hydrophobic
(i.e., has a high wetting angle), poor wetting of liquid
composition 106 can occur in the well near the containment
structure 102, and can result in thinning of the organic layer.
Although the organic layer may be thick enough to prevent
electrical shorting between electrodes, the thin organic layer at
the pixel edges can result in low rectification ratios and low
luminance efficiencies.
[0049] Coating, using ink jet printing or nozzle printing, of
materials over very low energy surfaces that form the active layers
in an OLED display is difficult. One set of such materials is the
DuPont DB series of buffer materials. The surface energy of a dried
film of DuPont's DB series of buffers is about 19 mN/m which is
very similar to that of Teflon.RTM.. This problem is particularly
noticeable when the containment structure is 1 .mu.m or less in
depth. There is a need in the art for improved coating methods for
forming such layers.
[0050] To meet this need, one embodiment, a process is provided for
forming an electronic device. The process comprises:
[0051] providing a substrate having at least one opening with a
cross-sectional view having a negative slope, wherein from a plan
view, each opening has a perimeter that substantially corresponds
to a perimeter of an organic electronic component; and
[0052] depositing a layer on a surface within the opening, said
surface having a surface energy of 30 mN/m or less.
[0053] In one embodiment, the surface energy is 25 mN/m or less. In
other embodiments, the surface energy is 20 mN/m or less. In still
other embodiments, the surface energy is 19 mN/m or less.
[0054] Is one embodiment, the opening is 1 .mu.m or less in
depth.
[0055] Also provided are electronic devices made by the methods
described herein.
[0056] In one embodiment, an electronic device includes a
substrate, a structure having openings, and a first electrode
overlying the structure and lying within the openings. From a
cross-sectional view, the structure, at the openings, has a
negative slope. From a plan view, each opening has a perimeter that
substantially corresponds to a perimeter of an organic electronic
component. Portions of the first electrode overlying the structure
and lying within the openings are connected to each other. Devices
using a substrate with openings, having a negative slope from a
cross-sectional view are found in U.S. patent application Ser. No.
10/910,496, filed on Aug. 3, 2004, the contents of which is
incorporated by reference herein in their entirety.
[0057] In general, if a liquid medium has a contact angle on a
given surface that is higher than about 40 degrees, this is because
the surface energy of the liquid medium is too high relative to the
surface energy of the surface. Thus, a desired contact angle can be
achieved by either lowering the surface energy of the liquid
medium, or raising the surface energy of the surface. In some
embodiments, when the surface energy of the surface is low, a
solvent of relatively low surface energy is preferred. The matching
of these surface energies is discussed in published U.S. Patent
Application No. 2005-0062021 A1 (U.S. patent application Ser. No.
10/669,403, filed Sep. 24, 2003), the contents of which is
incorporated by reference herein in its entirety.
[0058] As discussed herein, the use of a substrate with an undercut
structure, with a low surface energy substrate, can be used to
provide improved layer formation.
[0059] In one exemplary embodiment, a surface of the structure is
hydrophobic. In a further exemplary embodiment, a second electrode
lies between the substrate and the structure. In an additional
embodiment, the second electrode has a surface that is hydrophilic.
In another exemplary embodiment, the substrate includes a driver
circuit coupled to the organic electronic component.
[0060] In one embodiment, an electronic device includes a
substrate, a first structure overlying the substrate, and a second
structure overlying the substrate. From a cross-sectional view, the
first structure has a negative slope and, from a plan view, the
first structure has a first pattern. From a cross-sectional view,
the second structure has a negative slope and, from a plan view,
the second structure has a second pattern different from the first
pattern. The first structure has a portion that contacts the second
structure.
[0061] In one embodiment, the first structure includes openings,
wherein, from a plan view, each opening has a perimeter that
substantially corresponds to a perimeter of an organic electronic
component. In one embodiment, the electronic device includes an
electrode overlying at least portions of the first structure and
the second structure. In one embodiment, the electrode lies within
the openings and is continuous between the openings. In one
embodiment, the second structure has a thickness at least 1.5 times
greater than a thickness of the first structure. In one embodiment,
the first structure has a thickness no more than about 3
micrometers.
[0062] In one embodiment, the second structure has a thickness at
least 3 micrometers. In one embodiment, the electronic device
includes an electrode between the substrate and the first
structure. In one embodiment, the electrode has a surface that is
hydrophilic. In one embodiment, the electronic device comprises a
passive matrix display. In one embodiment, the first structure and
the second structure have surfaces that are hydrophobic.
[0063] In one embodiment, a process for forming an electronic
device includes forming a structure having a negative slope and
openings. From a plan view, each opening has a perimeter that
substantially corresponds to a perimeter of an organic electronic
component. The process also includes depositing an organic active
layer within the openings. The organic active layer has a liquid
composition. The process further includes forming a first electrode
overlying the structure and the organic active layer and lying
within the openings. Portions of the first electrode overlying the
structure and lying within the openings are connected to each
other.
[0064] In one embodiment, the process includes forming a second
electrode before forming the structure, wherein after forming the
structure, portions of the second electrode are exposed along the
bottoms of the openings. In one embodiment, the liquid composition
contacts the second electrode at a wetting angle of less than 90
degrees. In one embodiment, the liquid composition contacts the
structure at a wetting angle of at least 45 degrees.
[0065] For each of the exemplary embodiments disclosed above, the
organic electronic components may include an organic active
layer.
[0066] Other features and advantages of the invention will be
apparent from the following detailed description, and from the
claims. The detailed description first addresses Definitions
followed by Structures, Layers and Components of an Electronic
device, Process for Forming Electronic Devices, and Other
Embodiments.
[0067] The aforementioned solutions can be applied by any solution
pattering method and device used in the art for making of such
layers. These devices use a variety of techniques, including
sequentially depositing the individual layers on a suitable
substrate. Substrates such as glass and polymeric films can be
used. Conventional vapor deposition techniques can be used, such as
thermal evaporation, chemical vapor deposition, and the like.
Alternatively, the organic layers can be applied by liquid
deposition using suitable solvents. The liquid can be in the form
of solutions, dispersions, or emulsions. Typical liquid deposition
techniques include, but are not limited to, continuous deposition
techniques such as spin coating, gravure coating, curtain coating,
dip coating, slot-die coating, spray-coating, and continuous nozzle
coating; and discontinuous deposition techniques such as ink jet
printing, gravure printing, and screen printing, any conventional
coating or printing technique, including but not limited to
spin-coating, dip-coating, roll-to-roll techniques, ink jet
printing, screen-printing, gravure printing and the like. In some
embodiments, an ink jet printing method is preferred. In other
embodiments, a nozzle printer application is preferred.
[0068] Any solvent may be used that solubilizes the materials that
form the coated layer. In some embodiments, the solvent is
preferably an aprotic solvent. In one embodiment, the solvent is an
aromatic hydrocarbon. In another embodiment, the aprotic organic
solvent is toluene, xylene, mesitylene, anisole, chlorobenzene,
cyclohexanone, gamma-valerolactone, or chloroform, or derivatives
thereof. In some embodiments, the solvent is preferably toluene. In
yet other embodiments, the solvent is a fluorinated solvent.
Certain of these fluorinated solvents are phenolic compounds that
contain one or more fluoro substituents. Certain of these solvents
are disclosed in U.S. patent application Ser. No. 10/669,404 filed
on Sep. 24, 2003, the contents of which is incorporated herein by
reference herein in its entirety.
[0069] The devices and methods are widely applicable to a broad
range of charge transport and emissive materials, including small
molecule emissive materials. Many charge transport materials and
emissive materials are known to those skilled in the art. Certain
illustrative examples are discuss herein.
[0070] Many aspects and embodiments have been described above and
are merely exemplary and not limiting. After reading this
specification, skilled artisans appreciate that other aspects and
embodiments are possible without departing from the scope of the
invention.
[0071] Other features and benefits of any one or more of the
embodiments will be apparent from the following detailed
description, and from the claims. The detailed description first
addresses Definitions and Clarification of Terms followed by
Structures, Layers, and Components of an Electronic Device, and
Process for Forming Electronic Devices.
1. DEFINITIONS AND CLARIFICATION OF TERMS
[0072] Before addressing details of embodiments described below,
some terms are defined or clarified.
[0073] "Surface energy" is a property arising from unbalanced
molecular cohesive forces at or near a surface. The molecules at
the surface of a liquid experience a net attractive force pointing
toward the liquid interior. This net attractive force causes the
liquid surface to contract toward the interior until repulsive
collisional forces from the other molecules halt the contraction at
a point when the surface area is a minimum. There is an increase in
potential energy when a molecule is taken from the bulk and placed
at the surface, work must be done to create any new surface.
[0074] The work .delta.w, required to create a new surface is
proportional to the number of molecules brought from the bulk to
the surface, and hence, to the area .delta.A, of the new surface,
so that w.varies..delta.A or
.delta.w=.gamma..delta.A
where .gamma., the constant of proportionality, is defined as the
surface energy or the specific surface free energy. Note that is
has dimensions of force per unit length and for a pure liquid it is
numerically equal to the surface tension. .gamma. is normally
measured in millinewtons per meter (mN/m), equivalent to the c.g.s
unit of dyne per centimeter (dyne/cm).
[0075] The surface tensions of liquids can be measured using a
tensiometer. A platinum plate is lowered into the liquid being
measured and slowly pulled again, the force per unit length exerted
on the plate as it exits the liquid is measured on a scale and that
is the surface tension of the liquid.
[0076] The term "organic electronic device" is intended to mean a
device including one or more semiconductor layers or materials.
Organic electronic devices include, but are not limited to: (1)
devices that convert electrical energy into radiation (e.g., a
light-emitting diode, light emitting diode display, diode laser, or
lighting panel), (2) devices that detect signals through electronic
processes (e.g., photodetectors photoconductive cells,
photoresistors, photoswitches, phototransistors, phototubes,
infrared ("IR") detectors, or biosensors), (3) devices that convert
radiation into electrical energy (e.g., a photovoltaic device or
solar cell), and (4) devices that include one or more electronic
components that include one or more organic semiconductor layers
(e.g., a transistor or diode). The term device also includes
coating materials for memory storage devices, antistatic films,
biosensors, electrochromic devices, solid electrolyte capacitors,
energy storage devices such as a rechargeable battery, and
electromagnetic shielding applications.
[0077] The term "substrate" is intended to mean a workpiece that
can be either rigid or flexible and may include one or more layers
of one or more materials, which can include, but are not limited
to, glass, polymer, metal, or ceramic materials, or combinations
thereof.
[0078] The term "active" when referring to a layer or material is
intended to mean a layer or material that exhibits electronic or
electro-radiative properties. An active layer material may emit
radiation or exhibit a change in concentration of electron-hole
pairs when receiving radiation. Thus, the term "active material"
refers to a material which electronically facilitates the operation
of the device. Examples of active materials include, but are not
limited to, materials which conduct, inject, transport, or block a
charge, where the charge can be either an electron or a hole.
Examples of inactive materials include, but are not limited to,
planarization materials, insulating materials, and environmental
barrier materials.
[0079] The term "active matrix" is intended to mean an array of
electronic components and corresponding driver circuits within the
array.
[0080] The terms "array," "peripheral circuitry," and "remote
circuitry" are intended to mean different areas or components of an
electronic device. For example, an array may include pixels, cells,
or other structures within an orderly arrangement (usually
designated by columns and rows). The pixels, cells, or other
structures within the array may be controlled by peripheral
circuitry, which may lie on the same substrate as the array but
outside the array itself. Remote circuitry typically lies away from
the peripheral circuitry and can send signals to or receive signals
from the array (typically via the peripheral circuitry). The remote
circuitry may also perform functions unrelated to the array. The
remote circuitry may or may not reside on the substrate having the
array.
[0081] The term "base" is intended to mean a portion of a layer,
member, structure, or a combination thereof that is supported by an
underlying layer, member, structure, or combination thereof.
[0082] The term "central portion" is intended to mean a portion of
an area that is surrounded by an exclusion portion for the same
area. In one embodiment, the central portion can be the entire
portion surrounded by the exclusion portion or may be a portion of
such entire portion.
[0083] The term "circuit" is intended to mean a collection of
electronic components that collectively, when properly connected
and supplied with the proper potential(s), performs a function. A
circuit may include an active matrix pixel within an array of a
display, a column or row decoder, a column or row array strobe, a
sense amplifier, a signal or data driver, or the like.
[0084] The term "connected," with respect to electronic components,
circuits, or portions thereof, is intended to mean that two or more
electronic components, circuits, or any combination of at least one
electronic component and at least one circuit do not have any
intervening electronic component lying between them. Parasitic
resistance, parasitic capacitance, or both are not considered
electronic components for the purposes of this definition. In one
embodiment, electronic components are connected when they are
electrically shorted to one another and lie at substantially the
same voltage. Note that electronic components can be connected
together using fiber optic lines to allow optical signals to be
transmitted between such electronic components.
[0085] The term "containment structure" is intended to mean a
structure overlying a substrate, wherein the structure serves a
principal function of separating an object, a region, or any
combination thereof within or overlying the substrate from
contacting a different object or different region within or
overlying the substrate.
[0086] The term "coupled" is intended to mean a connection,
linking, or association of two or more electronic components,
circuits, systems, or any combination of at least two of: (1) at
least one electronic component, (2) at least one circuit, or (3) at
least one system in such a way that a signal (e.g., current,
voltage, or optical signal) may be transferred from one to another.
Non-limiting examples of "coupled" can include direct connections
between electronic components, circuits or electronic components
with switch(es) (e.g., transistor(s)) connected between them, or
the like.
[0087] The term "driver circuit" is intended to mean a circuit
configured to control the activation of an electronic component,
such as an organic electronic component.
[0088] The term "electrically continuous" is intended to mean a
layer, member, or structure that forms an electrical conduction
path without an electrical open circuit.
[0089] The term "electrode" is intended to mean a structure
configured to transport carriers. For example, an electrode may be
an anode, a cathode. Electrodes may include parts of transistors,
capacitors, resistors, inductors, diodes, organic electronic
components and power supplies.
[0090] The term "electronic component" is intended to mean a lowest
level unit of a circuit that performs an electrical or
electro-radiative (e.g., electro-optic) function. An electronic
component may include a transistor, a diode, a resistor, a
capacitor, an inductor, a semiconductor laser, an optical switch,
or the like. An electronic component does not include parasitic
resistance (e.g., resistance of a wire) or parasitic capacitance
(e.g., capacitive coupling between two conductors electrically
connected to different electronic components where a capacitor
between the conductors is unintended or incidental).
[0091] The term "exclusion portion" is intended to mean a portion
of an area that is not considered when characterizing such area.
For example, a portion of an area immediately adjacent to a
perimeter of the area may be include a transition region, wherein a
composition, thickness, other parameter, or any combination thereof
changes from the perimeter to another portion of the area
space-apart from the perimeter. In one embodiment, 10% of an area
may be an exclusion portion, and in another embodiment, 5% of an
area may be an exclusion portion.
[0092] The term "hydrophilic" is intended to mean that an edge of a
liquid exhibits a wetting angle less than 90 degrees with respect
to a surface that it contacts.
[0093] The term "hydrophobic" is intended to mean that an edge of a
liquid exhibits a wetting angle of 90 degrees or more with respect
to a surface that it contacts.
[0094] The term "layer" is used interchangeably with the term
"film" and refers to a coating covering a desired area. The area
can be as large as an entire device or a specific functional area
such as the actual visual display, or as small as a single
sub-pixel. Films can be formed by any conventional deposition
technique, including vapor deposition and liquid deposition. Liquid
deposition techniques include, but are not limited to, continuous
deposition techniques such as spin coating, gravure coating,
curtain coating, dip coating, slot-die coating, spray-coating, and
continuous nozzle coating; and discontinuous deposition techniques
such as ink jet printing, gravure printing, and screen
printing.
[0095] The term "liquid composition" is intended to mean a liquid
medium in which a material is dissolved to form a solution, a
liquid medium in which a material is dispersed to form a
dispersion, or a liquid medium in which a material is suspended to
form a suspension or an emulsion.
[0096] The term "liquid medium" is intended to mean a liquid
material, including a pure liquid, a combination of liquids, a
solution, a dispersion, a suspension, and an emulsion. Liquid
medium is used regardless whether one or more solvents are
present.
[0097] The term "negative," with respect to slope, is intended to
mean an angle formed between (1) a wall of layer, member,
structure, or a combination thereof and (2) a reference plane is an
acute angle.
[0098] The term "organic active layer" is intended to mean one or
more organic layers, wherein at least one of the organic layers, by
itself, or when in contact with a dissimilar material is capable of
forming a rectifying junction.
[0099] The term "orientation" is intended to mean a direction lying
along a line. In one embodiment, a column can correspond to one
orientation and a row can correspond to another orientation. In
still another embodiment, a diagonal line can correspond to an
orientation.
[0100] The term "opening" is intended to mean an area characterized
by the absence of a particular structure that surrounds the area,
as viewed from the perspective of a plan view.
[0101] The term "organic electronic device" is intended to mean a
device including one or more semiconductor layers or materials.
Organic electronic devices include: (1) devices that convert
electrical energy into radiation (e.g., an light-emitting diode,
light emitting diode display, or diode laser), (2) devices that
detect signals through electronics processes (e.g., photodetectors
(e.g., photoconductive cells, photoresistors, photoswitches,
phototransistors, or phototubes), IR detectors, or biosensors), (3)
devices that convert radiation into electrical energy (e.g., a
photovoltaic device or solar cell), and (4) devices that include
one or more electronic components that include one or more organic
semiconductor layers (e.g., a transistor or diode).
[0102] The term "overlying," when used to refer to layers, members
or structures within a device, does not necessarily mean that one
layer, member or structure is immediately next to or in contact
with another layer, member, or structure.
[0103] The term "passive matrix" is intended to mean an array of
electronic components, wherein the array does not have any driver
circuits.
[0104] The term "perimeter" is intended to mean a boundary of a
layer, member, or structure that, from a plan view, forms a closed
planar shape.
[0105] The term "polymer" is intended to mean a material having at
least one repeating monomeric unit. The term includes homopolymers
having only one kind of monomeric unit, and copolymers having two
or more different monomeric units. Copolymers are a subset of
polymers. In one embodiment, a polymer has at least 5 repeating
units.
[0106] The term "primary surface" is intended to mean a surface of
a substrate from which an electronic component is subsequently
formed.
[0107] The term "radiation-emitting component" is intended to mean
an electronic component, which when properly biased, emits
radiation at a targeted wavelength or spectrum of wavelengths. The
radiation may be within the visible-light spectrum or outside the
visible-light spectrum (UV or IR). A light-emitting diode is an
example of a radiation-emitting component.
[0108] The term "radiation-responsive component" is intended to
mean an electronic component, which when properly biased, can
respond to radiation at a targeted wavelength or spectrum of
wavelengths. The radiation may be within the visible-light spectrum
or outside the visible-light spectrum (UV or IR). An IR sensor and
a photovoltaic cell are examples of radiation-sensing
components.
[0109] The term "rectifying junction" is intended to mean a
junction within a semiconductor layer or a junction formed by an
interface between a semiconductor layer and a dissimilar material,
in which charge carriers of one type flow easier in one direction
through the junction compared to the opposite direction. A pn
junction is an example of a rectifying junction that can be used as
a diode.
[0110] The term "slope" is intended to mean an angle formed between
(1) a wall of layer, member, structure, or a combination thereof
and (2) a reference plane. In one embodiment, the reference plane
can be the primary surface of the substrate. An overall slope can
be the angle formed by the reference plane and a line that includes
the two endpoints of the wall, such as a proximate point that lies
closest to the substrate and a distal point that lies furthest from
the substrate along the wall. An initial slope can be the angle
formed by the reference plane and a line that includes the proximal
point and an intermediate point along the wall and spaced-part from
the proximal point, wherein the distal point lies further from the
proximal point as compared to the intermediate point.
[0111] The term "substrate" is intended to mean a workpiece that
can be either rigid or flexible and may include one or more layers
of one or more materials, which can include, but are not limited
to, glass, polymer, metal or ceramic materials or combinations
thereof.
[0112] The term "substrate structure" is intended to mean a
structure overlying a substrate, wherein the structure serves a
principal function of separating an area or region into smaller
areas or regions. A substrate structure can include a cathode
separator or a well structure.
[0113] The term "sulfonated polymer" is intended to mean a polymer
that has been exposed to a sulfonic acid or incorporates a
sulfonate radical of a corresponding sulfonic acid.
[0114] The term "wetting angle" is intended to mean a tangent angle
at the edge interface between a gas, a liquid and a solid surface
as measured from the solid surface through the liquid to a
gas/liquid interface.
[0115] As used herein, the terms "comprises," "comprising,"
"includes," "including," "has," "having" or any other variation
thereof, are intended to cover a non-exclusive inclusion. For
example, a process, method, article, or apparatus that comprises a
list of elements is not necessarily limited to only those elements
but may include other elements not expressly listed or inherent to
such process, method, article, or apparatus. Further, unless
expressly stated to the contrary, "or" refers to an inclusive or
and not to an exclusive or. For example, a condition A or B is
satisfied by any one of the following: A is true (or present) and B
is false (or not present), A is false (or not present) and B is
true (or present), and both A and B are true (or present).
[0116] The use of "a" or "an" are employed to describe elements and
components of the invention. This is done merely for convenience
and to give a general sense of the invention. This description
should be read to include one or at least one and the singular also
includes the plural unless it is obvious that it is meant
otherwise.
[0117] Group numbers corresponding to columns within the Periodic
Table of the elements use the "New Notation" convention as seen in
the CRC Handbook of Chemistry and Physics, 81st Edition
(2000-2001).
[0118] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of embodiments of the
present invention, suitable methods and materials are described
below. All publications, patent applications, patents, and other
references mentioned herein are incorporated by reference in their
entirety, unless a particular passage is cited. In case of
conflict, the present specification, including definitions, will
control. In addition, the materials, methods, and examples are
illustrative only and not intended to be limiting.
[0119] To the extent not described herein, many details regarding
specific materials, processing acts, and circuits are conventional
and may be found in textbooks and other sources within the organic
light-emitting diode display, photodetector, photovoltaic, and
semiconductive member arts.
2. STRUCTURES, LAYERS, AND COMPONENTS OF AN ELECTRONIC DEVICE
[0120] FIG. 1 illustrates a plan view of a prior art structure 102
and FIG. 2 illustrates a cross-sectional view of the prior art
structure 102. The structure 102 has a perimeter having a positive
slope as seen from the cross-sectional view of FIG. 2. When a
liquid composition 106 is deposited into the well formed by the
surrounding structure 102, it may form voids. Such voids decrease
the available surface area for radiation emission or radiation
absorption, leading to reduced performance. Voids, such as void
108, may also expose underlying structures 104, such as electrodes.
When additional layers are formed over organic layers resulting
from curing the liquid composition, these layers may contact the
underlying structure 104, permitting electrical shorting between
electrodes and rendering an affected organic electronic component
inoperable.
[0121] In addition, if structure 102 is hydrophobic (i.e., has a
high wetting angle), poor wetting of liquid composition 106 can
occur in the well near the structure 102, and can result in
thinning of the organic layer. Although the organic layer may be
thick enough to prevent electrical shorting between electrodes, the
thin organic layer at the pixel edges can result in low
rectification ratios and low luminance efficiencies.
[0122] Coating, using ink jet printing or nozzle printing, of
materials over very low energy surfaces that form the active layers
in an OLED display is difficult. One set of such materials is the
DuPont DB series of buffer materials. The surface energy of a dried
film of DB-1 is about 19 mN/m which is very similar to that of
Teflon.RTM.. This problem is particularly noticeable when the well
is 1 .mu.m or less in depth.
[0123] In a particular embodiment, an electronic device includes an
array of organic electronic components and a structure having
openings that correspond to a perimeter of each of the organic
electronic components when viewed from a plan view. The structure
has a negative slope at the openings when viewed from a
cross-sectional view. Each organic electronic component may include
first and second electrodes (e.g. an anode and a cathode) separated
by one or more layers including an organic active layer. In one
embodiment, the exemplary electronic device may also include a
second structure that has a negative slope, such as an electrode
separator (e.g., cathode separator).
[0124] In one exemplary embodiment, the array of organic electronic
components may be part of a passive matrix. In another exemplary
embodiment, the array of organic electronic components may be part
of an active matrix. As such, exemplary embodiments of the
electronic device may include active matrix and passive matrix
displays.
[0125] Generally, each organic electronic component includes two
electrodes separated by one or more organic active layers. In
addition, other layers, such as hole-transport layers and
electron-transport layers, may be included between the two
electrodes. Structures having openings that correspond to the
perimeter of each of the organic electronic components define
containment structures, within which portions of the organic
electronic components are formed.
[0126] The cross-section of the containment structures may
influence organic layer formation. FIG. 3 illustrates a
cross-sectional view of an exemplary structure 302. The structure
302 has a negatively sloped wall or perimeter 304 and forms an
acute angle with underlying structure 308. FIG. 4 illustrates a
portion of a perimeter of an exemplary structure 402 that forms an
acute angle .alpha. (alpha) between the surface of an underlying
structure 406 and the structure wall 404. In one exemplary
embodiment, the angle .alpha. (alpha) is between 0.degree. and
90.degree., such as between 0.degree. and 60.degree. or between
10.degree. and 45.degree.. In an alternative embodiment, the angle
.alpha. (alpha) may be about equal to or greater than the capillary
angle.
[0127] As illustrated in FIG. 5, when a liquid composition 306 is
deposited into the perimeter of an opening formed by the structure
302, fingers 310 can be seen. As the opening within structure 302
fills, the liquid composition forms a layer without voids. FIG. 6
illustrates a plan view of a filled opening, and FIG. 7 illustrates
a cross-sectional view at sectioning line 7-7 of FIG. 6. When the
liquid composition 306 is deposited along the perimeter 304, it
covers the underlying structure 308. In one exemplary embodiment,
the liquid forms a layer that is substantially more uniform as
compared to a similar structure and liquid composition as
illustrated in FIGS. 1 and 2.
[0128] Regarding the structure of FIG. 4, FIG. 8 illustrates a
layer 808 formed overlying surface 406. A liquid composition may be
deposited and the solvent extracted to form layer 808. As is
illustrated, layer 808 contacts structure wall 404 and covers
surface 406. Electronic devices including such a layer are less
likely to short. In addition, the more uniform layer reduces the
likelihood of poor device performance characteristics (e.g., low
rectification ratio, low luminance efficiency, etc.) found in
devices where thinning of the organic layers near the containment
structures is observed.
[0129] In one embodiment, an electronic device includes a
substrate, a first structure having a negative slope, and a second
structure having a negative slope when viewed from a
cross-sectional view. The first structure overlies the substrate
and, from a plan view, has a first pattern. The second structure
overlies the substrate and, from a plan view, has a second pattern
that is different from the first. In one embodiment, the first
structure is a containment structure, an array of openings within
which organic electronic components may be formed. The second
structure may, for example, be an electrode separator
structure.
[0130] In another embodiment, from a plan view, each opening within
the first structure has a perimeter that substantially corresponds
to a perimeter of an organic electronic component.
[0131] In one example, the second structure may have a thickness
between approximately 3 and 10 micrometers. The first structure may
have a thickness less than 3 micrometers, such as between
approximately 1 and 3 micrometers or less than 1 micrometer such as
approximately 0.4 micrometer. The second structure may, for
example, have a thickness at least 1.5 times greater than that of
the first structure.
[0132] In another embodiment, an electronic device includes a
substrate, a structure (e.g., a containment structure), and a first
electrode. The structure has openings and, when viewed from a
cross-sectional view, has a negative slope at the openings. From a
plan view, each of the openings has a perimeter that substantially
corresponds to a perimeter of an organic electronic component. The
first electrode overlies the structure and lies within the
openings. Portions of the first electrode overlying the structure
and lying within the openings are connected to each other. In a
particular example, the organic electronic component may include
one or more organic active layers. In one embodiment, the first
electrode may be a common electrode (e.g., common cathode or common
anode for an array of organic electronic components). In another
exemplary embodiment, a second electrode may lie between the
substrate and the structure. In a further exemplary embodiment, the
organic electronic component may be coupled to a driver circuit
(not illustrated) lying within the substrate. Note that the second
electrode may be formed before the first electrode in one
embodiment.
[0133] In one exemplary embodiment, the structure or structures
having the negative slope have substantially hydrophobic surfaces.
The surfaces exhibit wetting angles with liquid compositions
greater than 45.degree., such as 90.degree. or higher. In contrast,
underlying structures, such as electrodes, may have substantially
hydrophilic surfaces, exhibiting wetting angles of liquid
compositions less than 90.degree., such as less than 60.degree., or
between approximately 0.degree. and about 45.degree..
3. PROCESS FOR FORMING ELECTRONIC DEVICES
[0134] An exemplary process for forming electronic devices includes
forming one or more structures that overlie a substrate and have a
negative slope from a cross-sectional perspective. One exemplary
process is illustrated in FIGS. 9 through 23, which can be used for
a passive matrix display. Variations on this process may be used to
form other electronic devices.
[0135] FIG. 9 depicts a plan view of a portion of an exemplary
process sequence, and FIG. 10 depicts a cross-sectional view of the
portion as viewed from sectioning line 10-10 in FIG. 9. Electrodes
904 are deposited on a substrate 902. The substrate 902 may be a
glass or ceramic material or a flexible substrate comprising at
least one polymer film. In one exemplary embodiment, the substrate
902 is transparent. Optionally, the substrate 902 may include a
barrier layer, such as a uniform barrier layer or a patterned
barrier layer.
[0136] The electrodes 904 may be anodes or cathodes. FIG. 9 depicts
the electrodes 904 as parallel strips. Alternately, the electrodes
904 may be a patterned array of structures having plan view shapes,
such as squares, rectangles, circles, triangles, ovals, and the
like. Generally, the electrodes may be formed using conventional
processes (e.g. deposition, patterning, or a combination
thereof).
[0137] The electrodes 904 may include conductive material. In one
embodiment, the conductive material may include a transparent
conductive material, such as indium-tin-oxide (ITO). Other
transparent conductive materials include, for example,
indium-zinc-oxide, zinc oxide, and tin oxide. Other exemplary
conductive materials include, zinc-tin-oxide (ZTO), elemental
metals, metal alloys, and combinations thereof. The electrodes 904
may also be coupled to conductive leads (not illustrated). In one
exemplary embodiment, the electrodes 904 may have hydrophilic
surfaces.
[0138] A subsequent layer may be deposited and patterned into
structures that, from a cross-sectional view, have a negative
slope. FIG. 11 depicts a plan view of this sequence in the process,
and FIG. 12 illustrates a cross-sectional view of the sequence. A
structure 1106 is formed that has openings 1108 and has a negative
slope at the openings 1108, as viewed from a cross-sectional view.
The openings 1108 may expose portions of electrodes 904. As seen
from the plan view, the bottom of the openings 1108 may include
portions of the electrodes 904 or may also encompass a portion of
the substrate 902.
[0139] In one exemplary embodiment, the structure 1106 may be
formed from resist or polymeric layers. The resist may, for
example, be a negative resist material or positive resist material.
The resist may be deposited on the substrate 902 and over the
electrodes 904. Typical liquid deposition techniques include, but
are not limited to, continuous deposition techniques such as spin
coating, gravure coating, curtain coating, dip coating, slot-die
coating, spray coating, and continuous nozzle coating; and
discontinuous deposition techniques such as ink jet printing,
gravure printing, and screen printing. The resist may be patterned
through selective exposure to radiation, such as ultraviolet (UV)
radiation. In one embodiment, the resist is spin deposited and
baked (not illustrated). The resist is exposed to UV radiation
through a mask (not illustrated), developed, and baked, leaving a
structure having a negative slope at the openings. The negative
slope can be achieved by (1) using a UV flood exposure (not
collimated) when using the masks or (2) overexposing the resist
layer while the mask lies between the resist layer and a radiation
source (not illustrated).
[0140] In another exemplary embodiment, a sacrificial structure may
be used. In one embodiment, a sacrificial layer is deposited and
patterned to form a sacrificial structure having a positive slope.
In a more specific embodiment, from a cross-sectional view, the
sacrificial structure has a complementary profile as compared to
the first structure 1106 that is subsequently formed. The thickness
of the sacrificial layer is substantially the same as the
subsequently formed first structure. In one embodiment, a
sacrificial layer is deposited over the first electrodes 904 and
the substrate 902. A patterned resist layer is formed over the
sacrificial layer using a conventional technique. In one specific
embodiment, a conventional resist-erosion etching technique is used
to form sloped sidewalls. In another specific embodiment, a
conventional isotropic etch is used. The patterned resist layer is
then removed using a conventional resist removal process.
[0141] Another layer that will be used for the first structure 1106
is deposited over the sacrificial structure and within openings in
the sacrificial structure. In one embodiment, that other layer has
a thickness at least as thick as the thickness of the sacrificial
structures. In other embodiment, that other layer is substantially
thicker than the sacrificial layer. Portions of the other layer
lying outside the sacrificial structure are removed using an
etching or polishing technique that is conventional within the
inorganic semiconductor arts. After the portions have been removed,
the first structure is formed. The sacrificial structure is then
removed to form the openings 1108 within the first structure
1106.
[0142] In one embodiment, the materials for the first and
sacrificial structures are different to allow the material of one
of the first and sacrificial structures to be removed selectively
compared to the other structure. Exemplary materials include
metals, oxides, nitrides, and resists. The material for the
sacrificial layer may be selected so that it can be selectively
removed from the substrate 902 without causing significant damage
to the first electrodes 904. After reading this specification,
skilled artisans will be able to choose materials that meet their
needs or desires.
[0143] After formation, the structure 1106 may have a pattern. The
pattern may, for example, be the pattern illustrated in FIG. 11.
Alternative patterns are illustrated in FIGS. 13 and 14. FIG. 13
illustrates a latticework pattern. FIG. 14 illustrates patterns
that may include oval shaped openings 1404 oriented across
underlying electrodes, circular openings 1406, and oval openings
1408 oriented along underlying electrodes, as viewed from a plan
view.
[0144] In another embodiment, another pattern may include columns
oriented substantially parallel to the lengths of electrodes 904.
Each of the columns has a negative slope and has at least a portion
covering the substrate 902 at locations adjacent to and between the
electrodes 904. A combination of the columns with
subsequently-formed electrode separator structures can result in
rectangular openings, from a plan view. The combination of
structures are formed before any one or more of the liquid
compositions are formed over the substrate.
[0145] A second structure may, optionally, be deposited over the
substrate 902 and the structure 1106. The second structure may or
may not contact portions of the electrodes 904 depending on the
pattern of the first structure 1106. The second structure may, for
example, be an electrode separator structure. FIGS. 15, 16, 17, and
18 illustrate an exemplary process sequence including the second
structures 1510. FIG. 15 illustrates a plan view including the
second structures 1510 oriented substantially perpendicular to the
electrode structures 904. FIG. 16 illustrates a cross-sectional
view between and parallel to the lengths of the second structures
1510 at sectioning line 16-16. FIGS. 17 and 18 illustrate
cross-sectional views perpendicular to the second structures 1510.
FIG. 17 illustrates a cross-sectional view through openings 1108 at
sectioning line 17-17, and FIG. 18 illustrates a cross-sectional
view away from openings 1108 at sectioning line 18-18.
[0146] As illustrated in FIGS. 17 and 18, the cross-sectional view
of the second structure 1510 has a negative slope. The second
structure 1510 may or may not encompass portions of the first
structure 1106 at the openings. In an alternate embodiment, the
second structure 1510 may be formed to entirely overlie the first
structure 1106. In general, the second structure 1510 may be formed
through techniques similar to those described in relation to the
first structure 1106.
[0147] Once the first structure 1106 and, optionally, the second
structure 1510 are formed, the electrodes 904 exposed via the
openings may be cleaned, such as through UV/ozone cleaning. The
structures 1108 and 1510 may be treated to produce hydrophobic
surfaces. For example, fluorine-containing plasma may be used to
treat the surfaces of the structures 1108 and 1510. The fluorine
plasma may be formed using gasses such as CF.sub.4, C.sub.2F.sub.6,
NF.sub.3, SF.sub.6, or combinations thereof. The plasma process may
include direct exposure plasma, or may use a downstream plasma. In
addition, the plasma may include O.sub.2. In one exemplary
embodiment, a fluorine-containing plasma may include 0-20% O.sub.2,
such as about 8% O.sub.2.
[0148] In one particular embodiment, the plasma is produced using a
March PX500 model plasma generator by March Plasma Systems of
Concord, Calif. The equipment is configured in flow through mode
with a perforated, grounded plate and a floating substrate plate.
In this embodiment, a 6-inch floating substrate plate is treated
with a plasma formed from a CF.sub.4/O.sub.2 gas composition. The
gas composition may include 80-100% CF.sub.4, such as approximately
92% CF.sub.4, and 0-20% O.sub.2, such as approximately 8% O.sub.2
by volume. The substrate may be exposed for 2-5 minutes, at a
pressure of 300-600 mTorr, using a 200-500 W plasma. For example,
the substrate may be exposed for approximately 3 minutes, at a
pressure of approximately 400 mTorr, using a plasma of
approximately 400 W.
[0149] FIGS. 19 and 20 illustrate an exemplary sequence in the
process in which an organic layer 1913 is deposited. The organic
layer 1913 may include one or more organic layers. In one
embodiment as illustrated in FIG. 20, the organic layer 1913
includes a charge transport layer 1914 and an organic active layer
1912. When present, the charge transport layer 1914 is formed over
the first electrodes 904 and before the organic active layer 1912
is formed. The charge transport layer 1914 can serve multiple
purposes. In one embodiment, the charge transport layer 1914 is a
hole-transport layer. Although not illustrated, an additional
charge transport layer may be formed over the organic active layer
1912. Therefore, the organic layer 1913 may include the organic
active layer 1912 and one, both or none of the charge transport
layers. Each of the charge transport layer 1914, organic active
layer 1912, and additional charge transport layer may include one
or more layers. In another embodiment, a single layer having a
graded or continuously changing composition may be used instead of
separate charge transport and organic active layers.
[0150] Returning to FIGS. 19 and 20, the charge transport layer
1914 and the organic active layer 1912 are formed sequentially over
the electrodes 904. Each of the charge transport layer 1914 and the
organic active layer 1912 can be formed by, for example, but not
limited to, continuous deposition techniques such as spin coating,
gravure coating, curtain coating, dip coating, slot-die coating,
spray coating, and continuous nozzle coating; discontinuous
deposition techniques such as ink jet printing, gravure printing,
and screen printing; casting; and vapor depositing. For example,
liquid compositions including the organic materials may be
dispensed through nozzles, such as micronozzles. One or both of the
charge transport layer 1914 and the organic active layer 1912 may
be cured after application.
[0151] In this embodiment, the charge transport layer 1914 is a
hole-transport layer. The hole-transport layer can be used to
potentially increase the lifetime and improve the reliability of
the device compared to a device where the conductive members 904
would directly contact the organic active layer 1912. In one
specific embodiment, the hole-transport layer can include an
organic polymer, such as polyaniline ("PANI"),
poly(3,4-ethylenedioxythiophene) ("PEDOT"), or an organic charge
transfer compound, such as tetrathiafulvalene
tetracyanoquinodimethane (TTF-TCQN). The hole-transport layer
typically has a thickness in a range of approximately 100-250
nm.
[0152] The hole-transport layer typically is conductive to allow
electrons to be removed from the subsequently formed active region
and transferred to the conductive members 904. Although the
conductive members 904 and the optional hole-transport layer are
conductive, typically the conductivity of the conductive members
904 is significantly greater than the hole-transport layer.
[0153] The composition of the organic active layer 1912 typically
depends upon the application of the organic electronic device. When
the organic active layer 1912 is used in a radiation-emitting
organic electronic device, the material(s) of the organic active
layer 1912 will emit radiation when sufficient bias voltage is
applied to the electrode layers. The radiation-emitting active
layer may contain nearly any organic electroluminescent or other
organic radiation-emitting materials.
[0154] Such materials can be small molecule materials or polymeric
materials. Small molecule materials may include those described in,
for example, U.S. Pat. No. 4,356,429 and U.S. Pat. No. 4,539,507.
Alternatively, polymeric materials may include those described in
U.S. Pat. No. 5,247,190, U.S. Pat. No. 5,408,109, and U.S. Pat. No.
5,317,169. Exemplary materials are semiconducting conjugated
polymers. An example of such a polymer is poly(phenylenevinylene)
("PPV"). The light-emitting materials may be dispersed in a matrix
of another material, with or without additives, but typically form
a layer alone. The organic active layer generally has a thickness
in the range of approximately 40-100 nm.
[0155] When the organic active layer 1912 is incorporated into a
radiation receiving organic electronic device, the material(s) of
the organic active layer 1912 may include many conjugated polymers
and electroluminescent materials. Such materials include, for
example, many conjugated polymers and electro- and
photo-luminescent materials. Specific examples include
poly(2-methoxy,5-(2-ethyl-hexyloxy)-1,4-phenylenevinylene)
("MEH-PPV") and MEH-PPV composites with CN--PPV. The organic active
layer 1912 typically has a thickness in a range of approximately
50-500 nm.
[0156] Although not illustrated, an optional electron-transport
layer may be formed over the organic active layer 1912. The
electron-transport layer is another example of a charge transport
layer. The electron-transport layer typically is conductive to
allow electrons to be injected from a subsequently formed cathode
and transferred to the organic active layer 1912. Although the
subsequently formed cathode and the optional electron-transport
layer are conductive, typically the conductivity of the cathode is
significantly greater than the electron-transport layer.
[0157] In one specific embodiment, the electron-transport layer can
include metal-chelated oxinoid compounds (e.g., Alq3);
phenanthroline-based compounds (e.g.,
2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ("DDPA"),
4,7-diphenyl-1,10-phenanthroline ("DPA")); azole compounds (e.g.,
2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole ("PBD"),
3-(4-biphenyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole
[0158] ("TAZ"); or any one or more combinations thereof.
Alternatively, the optional electron-transport layer may be
inorganic and comprise BaO, LiF, or Li.sub.2O. The
electron-transport layer typically has a thickness in a range of
approximately 30 nm to approximately 500 nm.
[0159] Any one or more of the charge transport layer 1914, organic
active layer 1912, and additional charge transport layer may be
applied as a liquid composition that includes one or more liquid
media. The hydrophobic and hydrophilic surfaces are specific with
respect to the liquid media within the liquid composition. In one
embodiment, the liquid composition may include a co-solvent
including, for example, alcohols, glycols, and glycol ethers. A
solvent for the organic active layer liquid media may be selected
such that it does not dissolve the charge transport layer.
Alternatively, the solvent may be selected such that the charge
transport layer is soluble or partially soluble in that
solvent.
[0160] In a particular embodiment, the negative slope of the
structure 1106 causes a capillary effect, drawing a liquid
composition of the organic material around the perimeter of the
openings 1108. Once cured, the organic active layer 1912 covers
underlying layers within the openings 1106, such as the electrodes
904 and charge transport layer 1914, preventing electrical shorting
between conductive members, such as electrodes (e.g., anodes and
cathodes).
[0161] A second electrode is formed over the organic layers 1913,
which in this embodiment includes the charge transport layer 1914
and the organic active layer 1912. FIG. 21 illustrates a plan view
of the process sequence and FIGS. 22 and 23 illustrate
cross-sectional views of the process sequence. In one embodiment, a
layer is deposited using a stencil mask to form conductive members
2118 on the second structures 1510 and forming electrodes 2116 over
organic active layers 1913 and over portions of the structure 1106.
The difference in elevation between electrode 2116 and conductive
members 2118 keeps them from being connected. As illustrated in
FIG. 22, electrode layer 2116 overlies layers within the openings
1108 and portions of the first structure 1106. The portions of
electrode layer 2116 overlying the layers within the openings 1108
and the portions of the electrode 2116 overlying portions of the
first structure 1106 are connected to each other to form an
electrically continuous structure.
[0162] In one embodiment, the electrodes 2116 act as cathodes. A
layer of the electrodes 2116 closest to the organic layer 1913 can
be selected from Group 1 metals (e.g., Li, Cs), the Group 2
(alkaline earth) metals, the rare earth metals including the
lanthanides and the actinides. The electrode layers 2116 and 2118
have a thickness in a range of approximately 300 nm to
approximately 600 nm. In one specific, non-limiting embodiment, a
Ba layer of less than approximately 10 nm followed by an Al layer
of approximately 500 nm may be deposited. The Al layer may be
replaced by or used in conjunction with any of the metals and metal
alloys.
[0163] As depicted in the FIGS. 21, 22, and 23, the organic
electronic components formed from an anode, such as electrode 904,
the organic layers 1913, and a cathode, such as electrode 2116 are
addressable via a peripheral circuitry. For example, applying a
potential across one selected row of electrodes 2116 and one
selected column of electrodes 904 activate one organic electronic
component.
[0164] An encapsulating layer (not illustrated) can be formed over
the array and the peripheral and remote circuitry to form a
substantially complete electrical device, such as an electronic
display, a radiation detector, and a photovoltaic cell. The
encapsulating layer may be attached at the rail such that no
organic layers lie between it and the substrate. Radiation may be
transmitted through the encapsulating layer. If so, the
encapsulating layer should be transparent to the radiation.
4. OTHER EMBODIMENTS
[0165] After formation of the organic electronic components, the
first structure 1106 and the second structures 1510 may optionally
be altered or removed. In one exemplary embodiment, the electronic
device may be heated to about a glass transition temperature of the
material forming structure 1106 or structures 1510. Such heating
may result in reflow, causing the slope of the structures to change
in the final device, as viewed from a cross-sectional perspective.
In another embodiment, an etch process may be used to remove
structures, such as structure 1106. As such, the cross-sectional
appearance of the final electronic device may be different than the
structures and layers depicted in FIGS. 21, 22, and 23.
[0166] The electronic device formed through the process illustrated
in FIGS. 9-23 is a passive matrix device. In an alternate
embodiment, the electronic device may be an active matrix device.
FIGS. 24 and 25 illustrate an exemplary active matrix device. FIG.
25 illustrates the cross section of an electronic component at
sectional lines 25-25 in FIG. 24. Each organic electronic component
2416 may include a unique electrode 2406 having an associated
driver circuit 2418. The driver circuit 2418 may be incorporated
into a substrate 2402 over which the unique electrode 2406 is
formed. A containment structure 2404 may have openings
corresponding to the perimeter of the organic electronic components
2416. Other structures, such as some of the other containment
structures described with respect to a passive matrix device, may
be used in other embodiments. The containment structure 2404 has a
negative slope at the openings when viewed from a cross-sectional
perspective. Organic layer 2408 may overlie the unique electrode
2406 and may include hole-transport layer 2412 and organic active
layer 2410. Optionally, the organic layer 2408 may include an
electron-transport layer (not illustrated). In addition, the
organic electronic components 2416 may include a common electrode
2414. Each organic electronic component 2416 may then be activated
through an active matrix mechanism, such as through the driver
circuits 2418.
[0167] In the various embodiments illustrated above, the electrodes
may be cathodes or anodes. For example, the electrode 904 may be an
anode or a cathode. Similarly, electrode 2116 may be an anode or a
cathode. In one particular embodiment electrode 904 is a
transparent anode overlying a transparent substrate 902. For
electronic display devices, radiation emitted from organic
electronic components may emit through the transparent anode and
the substrate. Alternately, the electrode 904 may be a transparent
cathode.
[0168] In another embodiment, the electrode 904 and the substrate
902 may be opaque or reflective. In this embodiment, electrode 2116
may be formed of a transparent material and, for radiation emitting
devices, radiation may be emitted from an organic electronic
component through electrode 2116.
[0169] In a further embodiment, the process for forming the
electronic device may be used in fabricating radiation responsive
devices, such as sensor arrays, photodetectors, photoconductive
cells, photoresistors, photoswitches, phototransistors, phototubes,
IR detectors, biosensors, photovoltaics or solar cells. Radiation
responsive devices may include a transparent substrate and
substrate side electrode. Alternatively, the radiation responsive
device may include a transparent overlying electrode. Examples of
photodetectors include photoconductive cells, photoresistors,
photoswitches, phototransistors, and phototubes, and photovoltaic
cells, for example as in Kirk-Othmer, Concise Encyclopedia of
Chemical Technology, 4th edition, p. 1537, (1999).
[0170] In still a further embodiment, the process for forming the
electronic device may be used for inorganic devices. In one
embodiment, a liquid composition for forming an inorganic layer may
be used and allow better coverage of the liquid composition
adjacent to the same or other structures having a negative
slope.
[0171] In the foregoing specification, the invention has been
described with reference to specific embodiments. However, one of
ordinary skill in the art appreciates that various modifications
and changes can be made without departing from the scope of the
invention as set forth in the claims below. Accordingly, the
specification and figures are to be regarded in an illustrative
rather than a restrictive sense and all such modifications are
intended to be included within the scope of the invention.
[0172] Benefits, other advantages, and solutions to problems have
been described above with regard to specific embodiments. However,
the benefits, advantages, solutions to problems, and any element(s)
that may cause any benefit, advantage, or solution to occur or
become more pronounced are not to be construed as a critical,
required, or essential feature or element of any or all of the
claims.
[0173] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, suitable methods and materials are described below. All
publications, patent applications, patents, and other references
mentioned herein are incorporated by reference in their entirety.
In case of conflict, the present specification, including
definitions, will control. In addition, the materials, methods, and
examples are illustrative only and not intended to be limiting.
[0174] In the foregoing specification, the concepts have been
described with reference to specific embodiments. However, one of
ordinary skill in the art appreciates that various modifications
and changes can be made without departing from the scope of the
invention as set forth in the claims below. Accordingly, the
specification and figures are to be regarded in an illustrative
rather than a restrictive sense, and all such modifications are
intended to be included within the scope of invention.
[0175] Many aspects and embodiments have been described above and
are merely exemplary and not limiting. After reading this
specification, skilled artisans appreciate that other aspects and
embodiments are possible without departing from the scope of the
invention.
[0176] Benefits, other advantages, and solutions to problems have
been described above with regard to specific embodiments. However,
the benefits, advantages, solutions to problems, and any feature(s)
that may cause any benefit, advantage, or solution to occur or
become more pronounced are not to be construed as a critical,
required, or essential feature of any or all the claims.
[0177] It is to be appreciated that certain features are, for
clarity, described herein in the context of separate embodiments,
may also be provided in combination in a single embodiment.
Conversely, various features that are, for brevity, described in
the context of a single embodiment, may also be provided separately
or in any subcombination. Further, reference to values stated in
ranges include each and every value within that range.
* * * * *